European Patent Application 110,638 (Powers et al), published June 13, 1984, discloses a process for obtaining aqueous stripper essences and stripper oils. In the Powers et al process, a feed juice obtained from conventional juice extractors and finishers is stripped with steam or inert gas to remove orange aroma/flavor volatiles. These stripped volatiles are then condensed at progressively colder temperatures typically in the range of 95.degree. to -50.degree. F. in three condensers cooled, respectively, by cooling tower water, glycol and ammonia. The resulting aroma/flavor condensate contains an aqueous phase and an oil phase. The aqueous phase is separated by centrifugation (and optionally concentrated) to obtain the aqueous stripper essence. The separated oil phase forms the stripper oil. The aqueous stripper essence and stripper oil can be added back to the stripped juice after it is concentrated (preferably using TASTE evaporators), together with pulp, peel oil and other aqueous essences to make an orange juice concentrate product.
U.S. Pat. Nos. 3,072,490, issued Jan. 8, 1963, 3,366,497, issued Jan. 30, 1968, and 3,428,463, issued Feb. 18, 1969, to Sargeant, disclose high density (65.degree. to 80.degree. Brix), low viscosity citrus juice concentrates obtained by low temperature evaporation using high frequency electrical energy. The '490 patent discloses that 65.degree. Brix concentrates made by the Sargeant method can have viscosities on the order of 2000 to 2500 centipoise at 75.degree. F.; even lower viscosity 65.degree. Brix concentrates (1200 to 1500 centipoise at 75.degree. F.) are disclosed in the '497 patent. In addition to low viscosity, the '463 patent discloses that concentrates having better flavor and stability and lower bacteria count can be made by the Sargeant method.
In the Sargeant method, the juice is concentrated through the application of high frequency electrical energy at a temperature no greater than about 85.degree. F. under a pressure, followed by spraying into an evaporating chamber under high vacuum to cause flash evaporation. Prior to this high frequency electrical energy concentration step, the juice can be preconcentrated by conventional steam evaporators up to a solids level of 55.degree. Brix. Even during this preconcentration step, the juice is not heated to a temperature higher than about 90.degree. F. In the '463 patent, the high density concentrate obtained can be sprayed into a stream of vapors from the first stage of a conventional steam evaporator to absorb the esters and flavoring elements present in this vapor steam.
U.S. Pat. No. 4,374,865 to Strobel, issued Feb. 22, 1983, discloses an orange juice concentrate which retains at least 65% of the aroma and flavor volatile compounds from the natural juice. In the Strobel process, juice extraction is carried out such that the raw juice has a peel oil content of from 0.01 to 0.03%. Rag and seed are separated from the juice and pulp in a finisher with the finished juice being separated into a pulp portion and a serum portion. The serum portion is concentrated by freeze concentration or sublimation concentration to a solids content of from about 35 to about 87%. The concentrated serum is then blended with the pulp fraction to produce the orange juice concentrate product.
Strobel states that the concentration of peel oil in the final orange juice concentrate product should not exceed 0.035 by percent. Example 1 discloses one such product having a peel oil content of 0.025%. Strobel also states that juice, pulp or concentrate is optionally pasteurized by heating to a temperature of from about 80.degree. to about 95.degree. C. for from about 3 to about 12 seconds. This pasteurization is conducted in a closed system such that there is no exposure to an oxidative atmosphere.